1. Field of the Invention
An object of the present invention is a mammograph which can be used in radiology and, more particularly, in medicine. A mammograph is an instrument designed to give an image of the tissue structures of a breast of a patient under examination. The invention is aimed at making it easier for X-ray technicians to operate instruments of this type, and, therefore, at increasing the comfort of a patient undergoing an X-ray examination of the breast with an instrument of this type.
2. Description of the Prior Art
A mammograph essentially comprise an X-ray tube and a work top. The radiation of X-rays from the tube is directed towards the work top, most often in a direction that is substantially perpendicular to this top. The work top has a surface designed to receive and support the breast to be X-rayed. Downstream from this surface with respect to the radiation, a housing is made beneath this top. It is designed to receive a cassette with a radiosensitive film to give an account of the X-ray examination. Possibly, a supporting plate, or pelote, transparent to X-radiation, is interposed between the focus of the tube and the work top in order to compress the breast being examined at the instant when the picture is taken. Because of this compression, the supporting plate is further provided with devices to relax the pressure as soon as the picture has been taken. The setting of a mammograph for the distance between the focus of the X-ray tube (in fact the X-ray tube itself) and the surface of the work top is defined in the factory. In principle, this distance is fixed. To be able to take differences in height among patients into account, these two fittings are mounted fixedly, in a jutting out position, on a post. The post can then be raised or brought down with respect to a mean position to take this difference in the height of patients into account. Furthermore, for certain examinations, the breast to be X-rayed has to be irradiated laterally. Hence, the post which supports the X-ray tube and the work top is solidly joined to a horizontal shaft. This set can then rotate around this shaft. For example, the post is swung by a quarter turn around the shaft so as to obtain horizontal alignment of the tube and the work top.
In practice, these mammographs have many drawbacks. For, it is known that the alignment of the rotation shaft is substantially at mid-height of the distance between the focus of the X-ray tube and the work top. In practice, it may even be placed as close as possible to the work top itself, so that no corrections have to be made in the height of the device when the side shots are taken. Consequently, when these side shots are taken, the X-ray tube juts out with respect to the instrument in a twofold way. Firstly, it juts out towards the front of the instrument, towards the front of the post as observed earlier. Secondly, it now also protrudes with respect to the shaft. Now, the X-ray tube with its control and insulation equipment is heavy. It naturally causes the shaft to rotate and the post to swing. To avoid having to install brakes to restrict the swinging of the post when the tube is in a position for taking lateral pictures, the common practice is to place a counterweight at the end of the post, in a position that is substantially symmetrical with the X-ray tube with respect to the shaft. This counterweight has two drawbacks. Firstly, it is bulky. For, since it is raised when the side shots are taken, it hampers the movement of the X-ray technician. Secondly, it helps make it difficult to manipulate the X-ray tube/work top unit when changing the incidence. For, the inertia of a device of this type is great. Since the unit is manipulated by hand, this inertia is too great to enable high working rates, namely to enable a large number of patients to be put before the instrument in a given period.
Furthermore, the X-ray examination of a breast can also be done with the injection of a contrast medium. For example, a product that is opaque to X-rays is injected through the nipple into the milk ducts, just when the shot is taken. The presence of the post, located directly before the breast, hampers this maneuver and is, at the same time, also troublesome for the patient. During this delicate operation, the patient may seek to make visual contact with the X-ray technician, which she cannot do because of the post which is between them.
Besides, there are other known upholding structures where the post is replaced by a stirrup suspended from the ceiling. The X-ray tube is held at the top of the stirrup. The work top is hooked, by its two side edges, to the ends of the legs of the stirrup. In this case, it is easy to reach the patient. But then, the handling of the suspension to bring the patient into positions corresponding to lateral or oblique incidence can only be motor driven. Consequently, it is slow, and the equipment itself is costly.
An object of the invention is to overcome these drawbacks by proposing a structure to hold, respectively, the X-ray tube and the work top, a structure which is better suited to being manipulated when changing incidence and enables satisfactory technical and psychological contact between the patient and the X-ray technician. In substance, the invention provides for replacing the stirrup by a ring. The X-ray tube is hooked to the top of the ring. Ends of arcs of the ring are then fixed laterally to the work top. The result thereof is that, in the arch which is formed within this circular stirrup and which somewhat overhangs the work top, it now becomes possible to reach the patient's breast while she can see the X-ray technician. Furthermore, it becomes far easier to manipulate the tube, the fixing point of which slides on the rim of the ring. It is easier to change incidence without coming up against great inertia. There is no longer any troublesome counterweight. Finally, the ring can be fixed to a post or to a rest which is vertically movable so as to be adaptable to the patient's height.
To make the X-ray technician's work even easier, the circular stirrup is suspended from a bracket which moves this unit away from the post. The X-ray technician can then stand below this bracket, between the patient and the cabinet containing all the instruments control elements.